Anomalous weak magnetism in superconducting YBa2Cu3O6+x

For some time now, there has been considerable experimental and theoretical effort to understand the role of the normal-state "pseudogap" phase in underdoped high-temperature cuprate superconductors. Recent debate has centered on the question of whether the pseudogap is independent of superconductivity. We provide evidence from zero-field muon spin relaxation measurements in YBa2Cu3O6+x for the presence of small spontaneous static magnetic fields of electronic origin intimately related to the pseudogap transition. Our most significant finding is that, for optimal doping, these weak static magnetic fields appear well below the superconducting transition temperature. The two compositions measured suggest the existence of a quantum critical point somewhat above optimal doping.     

Estimation of genetic parameters in a recurrent selection program in Apple

Combining ability was estimated for 8 tree and 11 agronomic traits in a multi-location apple genetics population to select individuals for the next cycle of selections. Families more than three standard errors away from the general mean were identified for each trait and extreme individuals (with regard to that trait) from those families were selected. On the whole, 148 individuals were chosen based upon individual traits and, in a few cases a combination of traits, in a way that maintains the original diversity within the population. Narrow-sense heritability estimated separately for each site for fruit ribbing, fruit russet, fruit overcolour amount and fruit weight ranged from 0.0–0.13, 0.05–0.58, 0.34–0.40 and 0.27–0.90 respectively. Phenotypic correlation and additive genetic correlation were small and from small to moderately high respectively, between pairs of traits. The implication of these genetic parameter estimates in apple breeding is discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Incompatibility as a new method for identification of pyrethrum clones

Summary Pyrethrum clones cannot be satisfactorily identified by morphological traits, or by contents or types of pyrethrins.In pyrethrum a sporophytic incompatibility system operates. Most clones are strongly self-incompatible and cross-compatible. This was used as the basis of a revised identification system. It is assumed that in self-incompatibility and cross-compatibility the clones are identical. To test this assumption 128 different genotypes were selfed and crossed in 86 combinations. Only two genotypes (1.6%) were self-compatible and only one cross (1.2%) was reciprocally cross-incompatible.Since only a restricted number of clones is recommended and therefore issued, the incompatibility test together with morphology, especially of the flower, ensures an entirely satisfactory identification. Two applications are given.     

Replication dynamics of the yeast genome

Oligonucleotide microarrays were used to map the detailed topography of chromosome replication in the budding yeast Saccharomyces cerevisiae. The times of replication of thousands of sites across the genome were determined by hybridizing replicated and unreplicated DNAs, isolated at different times in S phase, to the microarrays. Origin activations take place continuously throughout S phase but with most firings near mid-S phase. Rates of replication fork movement vary greatly from region to region in the genome. The two ends of each of the 16 chromosomes are highly correlated in their times of replication. This microarray approach is readily applicable to other organisms, including humans.     

The presence and location ofErwinia carotovora subsp.carotovora (Jones) Bergey et al. in the gut of adultDrosophila melanogaster (Meigen)

The potato blackleg bacteriumErwinia carotovora subsp.carotovora (Jones) Bergey et al. was found in feces and regurgitated material obtained from surface sterilized adult fruit flies,Drosophila melanogaster (Meigen), that had fed for five hours on nutrient agar cultures of the bacterium. The highest levels of bacteria were obtained from fecal material and it is likely that this is the source of most of the inoculum carried by these vectors. The bacteria were found to be present in the foregut, midgut, and hindgut ofD. melanogaster. The largest number of bacteria were in the foregut with the population level decreasing as distance down the digestive tract increased. It is probable that the association between the vector and the bacterium is accidental. The probability that the insect aids survival of the bacterium by protecting it from adverse environmental conditions is suggested.     

Phosphorylated human lectin galectin-3: analysis of ligand binding by histochemical monitoring of normal/malignant squamous epithelia and by isothermal titration calorimetry

The human lectin galectin-3 is a multifunctional effector with special functions in regulation of adhesion and apoptosis. Its unique trimodular organization includes the 12-residue N-terminal sequence, a substrate for protein kinase CK1-dependent phosphorylation. As a step towards elucidating its significance, we prepared phosphorylated galectin-3, labelled it and used it as a tool in histochemistry. We monitored normal and malignant squamous epithelia. Binding was suprabasal with obvious positive correlation to the degree of differentiation and negative correlation to proliferation. The staining pattern resembled that obtained with the unmodified lectin. Basal cell carcinomas were invariably negative. The epidermal positivity profile was akin to distribution of the desmosomal protein desmoglein, as also seen with keratinocytes in vitro . In all cases, binding was inhibitable by the presence of lactose, prompting further investigation of the activity of the lectin site by a sensitive biochemical method, i.e. isothermal titration calorimetry. The overall affinity and the individual enthalpic and entropic contributions were determined. No effect of phosphorylation was revealed. This strategic combination of histo- and biochemical techniques applied to an endogenous effector after its processing by a protein kinase thus enabled a detailed monitoring of the binding properties of the post-translationally modified lectin. It underscores the value of using endogenous lectins as a histochemical tool. The documented approach has merit for applications beyond lectinology.